[Emc-users] Single Phase Lathe spindle motor question

[Ted H. <las...@gm...>]

emc...@li... wrote:
> Message: 5
> Date: Mon, 7 Mar 2011 22:03:45 -0800
> From: "Clint Washburn"<cl...@cl...>
> Subject: [Emc-users] Single Phase Lathe spindle motor question
> To: "'Enhanced Machine Controller \(EMC\)'"
> 	<emc...@li...>
> Message-ID:<00bd01cbdd56$99811290$cc8337b0$@com>
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>
> I am in the process of converting my 1978 Hitachi Seiki CNC lathe to EMC.
> It currently has a 7.5 KW dc motor that used to be powered by FUJI SCR
> drive.  My first problem my house does not have 3 phase power.  I am having
> to work around this issue with my whole retrofit.  I wish to convert this to
> a 3 phase AC spindle.  What VFD's are people having success with as a
> spindle drive with single phase power?  Is it realistic to have a 10 hp 3
> phase spindle on single phase power?  or will I have to go with a spindle
> motor closer to around 7.5hp instead?  What is everyone's input on this?
>
> Clint Washburn
>    
Clint - I converted my Tsugami lathe (also 7.5Hp DC spindle) over to a 
5hp AC spindle - and for testing was running on single phase 220. My AB 
VFD would only get the motor up to about 70% speed (2200rpm) before 
going into Bus Undervolt Fault - I was running this directly from the 
front panel of the VFD without EMC intervention at the time, so there 
should have been little to no regen or accel/decel problems. The spindle 
was also under no load (from cutting) - so under a cut scenario, I'd 
expect the unit to fault just as soon as the insert entered the cut. The 
unit functions just fine under 3phase power, of course.
It may be worthwhile to note that although many VFDs with 3 phase input 
are built on a simple bridge-cap system, how they check the line-line 
voltage may differ, so going leg R-T instead of R-S (for example) may 
get you lucky. Alternatively, you may look at a separate DC supply, and 
feed the ?440 into the DC bus input on your VFD....assuming your VFD 
supports it. I can do this on my AB, apparently. I recall Rexroth 
(Bosch) did this with a lot of their high end servo and spindle drives, 
so did Mitsu - one central DC supply, with drives that connected to the 
buss, instead of all AC input units.
My instinct based only one one experience says you're going to have a 
challenge getting that 10hp spooled up on single phase.

BTW - where did you get a 208vac 10hp drive? By the time you get higher 
than 5hp, most are wanting 380-480 input....or you have to mortgage the 
house..... :-)

Best wishes,
Ted.